Sql 查询三个表不输出任何内容
我有三张表,如下面的屏幕截图所示: 但是当我想要执行以下查询时,我没有得到任何结果,即使三个表中都有数据: 以下是生成的代码:Sql 查询三个表不输出任何内容,sql,sql-server,database,Sql,Sql Server,Database,我有三张表,如下面的屏幕截图所示: 但是当我想要执行以下查询时,我没有得到任何结果,即使三个表中都有数据: 以下是生成的代码: SELECT Clients.ClientID, Clients.FirstName, Clients.Surname, Clients.Internal, Clients.Organisation, Clients.LandlineNo, Clients.MobileNo, Clients.Address1, Clients.Town,
SELECT Clients.ClientID, Clients.FirstName, Clients.Surname, Clients.Internal, Clients.Organisation, Clients.LandlineNo, Clients.MobileNo, Clients.Address1, Clients.Town,
Clients.Postcode, Clients.Email, Clients.NHS, Clients.PurchaseOrderNumber, Bookings.Date, Bookings.Timebegan, Bookings.Timefinished, Bookings.Price,
Bookings.Repeats, Bookings.Rweeks, Bookings.Rdays, Bookings.Rmonths, Bookings.Occurrences, Rooms.Roomname
FROM Clients INNER JOIN
Bookings ON Clients.ClientID = Bookings.ClientID INNER JOIN
Rooms ON Bookings.RoomID = Rooms.RoomID
查看以更好地了解要使用的内容
如果性能是一个问题,还有其他一些方法。因为您使用的是内部联接,所以所有表都需要包含数据。尝试将联接更改为左侧外部联接,然后查看是否得到所需的结果。非常感谢您的帮助
Try
SELECT *
FROM Clients LEFT OUTER JOIN
Bookings ON Clients.ClientID = Bookings.ClientID
LEFT OUTER JOIN Rooms ON Bookings.RoomID = Rooms.RoomID